The present invention relates to a fibrous material which can adsorb a large quantity of inorganic fine powders or inorganic short fibers in a paper-making technique. More particularly, the present invention relates to a fibrous material which can effectively produce flocs by mixing the inorganic fine powders or inorganic short fibers with the fibrous material previously dispersed in water and caused to disintegrate, said flocs being capable of being manufactured into paper and adsorbing the inorganic fine powders or inorganic short fibers on the surfaces of the fibrous material, and being employable in producing sheet material containing a large amount of the inorganic fine powders or inorganic short fibers with the fibrous material as a carrier.
Sheet materials containing inorganic fine powders or inorganic short fibers have been employed in a very wide field in which various properties inherent in the inorganic fine powders and the inorganic short fibers are utilized. For instance, sheet materials comprising clay, gypsum, portland cement, asbestos or the like as the inorganic fine powders or inorganic short fibers are employed as construction materials or interior materials such as fire insulation panels, nonflammable panels or the like. In the ceramics industry, the sheet materials are useful for manufacturing numerous ceramic products for use as ceramic wares, electronic devices, magnetic devices or the like, or catalyst supporters for rendering exhaust gases from automobiles nontoxic upon re-combustion, by firing thin sheet materials. In particular, these sheet materials provide ceramic wares in special forms and permit freedom from dust, leading to an improvement in operability and operating environment, by forming cermamic raw powders, glases, pigments or the like into sheets. The sheet materials can also be adapted to special paper, filters or the like, making maximum use of various properties inherent in the inorganic fine powders, such as adsorbability of activated carbon, conductivity of metal powders and so on. Use of the sheet materials for the recovery of sludges and heavy metals from waste water discharged from plants is also important.
It is a general procedure for manufacturing sheet materials containing such inorganic fine powders or inorganic short fibers that the fibrous materials are utilized as carriers for the inorganic fine powders. It is to be noted herein that what is referred to as the inorganic fine powders alone throughout the specification should be understood to include the inorganic short fibers, too, unless otherwise specified. As the sheet materials consisting only of the inorganic fine powders are very difficult to handle and nearly impossible to transport, a variety of procedures have been proposed. Specifically, there are known, for example, the method of coating the sheet material (for example, paper or film) with the inorganic fine powders or impregnating the inorganic fine powders in the sheet material, as described, for example, in Japanese Patent Publication No. 1,728/1977; the method of sheeting coarse flocs manufacturable into paper, said flocs being produced by the addition of chemicals such as a latex, a surface active agent, a flocculant or the like to a slurry of a mixture of the inorganic fine powders with the fibrous material, as described, for example, in Japanese Patent Publication No. 8,164/1970 and No. 5,328/1977; and the method of using cationic pulp as a carrier for the inorganic fine powders because the inorganic fine powders generally have a negative zeta potential in water, as described, for example, in Japanese Laid-Open Patent Application No. 104,945/1974.
There are drawbacks, however, in the method of coating the sheet material with the inorganic fine powders or impregnating the inorganic fine powders in the sheet material, in that it is difficult to increase the amount of the inorganic fine powders to be applied thereon or impregnated therein and distribute the inorganic fine powders homogeneously in the sheet material. The firing of these sheet materials sometimes presented problems in that they were not sintered to a sufficient extent or a deformation would occur during the firing.
The method of adding the chemicals to the slurry of the mixture of the fibrous material with the inorganic fine powders offers advantages in that the amount of the inorganic fine powders in the sheet material can be increased; however, it presents drawbacks in that the preparation, storage and management of the chemicals are laborious, and it is impractical to adapt the preparation of the sheet materials on a small scale for home or individual use because the amount of the chemicals to be added is so extremely small that the procedure for the addition is difficult.
The method of using the cationic pulp can offer advantages in that the step is rendered simple because the cationic pulp itself has the ability to adsorb the inorganic fine powders so that inorganic sheets can be prepared in an simple manner, however, it has drawbacks in that the pulp itself is rendered extremely expensive because numerous chemical treatment procedures are required for cationating the pulp, and there is a limit on the kind of fibrous material capable of being employed for this purpose.